What is a god particle in space

Interview with CERN physicist Dr. Matthias Schott

Part 2: About the HIGGS particle and the HIGGS mechanism

 

Triplet room:What is the HIGGS particle?

Dr. Matthias Schott: First of all, quite theoretically: The Higgs particle is a massive, scalar particle that is postulated by the standard model of particle physics. So far, however, it has not been proven in any experiment.

But now in detail: The so-called standard model of particle physics describes all previous experiments very, very well. A basis of the theory is that all forces (also called interactions) can be described by fields. An example of these fields are, for example, electromagnetic fields, which are described by the well-known Maxwell equations. Since the Standard Model is a quantum theory, these fields are quantized, i.e. a particle is assigned to each field. In the case of the electromagnetic field, the associated quanta are the photons. These photons serve as exchange particles that mediate the force between two electrically charged particles. It is similar with the Higgs particle. The quanta of the Higgs field are called Higgs bosons (i.e. Higgs particles), and these couple to particles that have mass.

Triplet room:How did you come up with the idea of ​​postulating a HIGGS particle?

Dr. Matthias Schott: Unfortunately, you have to go back a long way for this question: All (or at least a very large part of) physics that we know is based on some kind of symmetry: For example, conservation of momentum follows from the fact that it doesn't matter where in space I'm doing a certain experiment. Well, the Standard Model is also based on symmetries called gauge symmetries. If you want to give the particles of the Standard Model a mass, you naively simply write the mass of the particles in addition, similar to F = m * a. The problem is that this

 
Series of pictures: A little comic is supposed to show the HIGGS mechanism

Writing down changes the structure of the equations so that they are no longer gauge symmetrical. With this the whole theory loses its basis in a certain way and one can no longer use the theory to make predictions. So you needed another method to give the particles mass in the Standard Model, and that's where Peter Higgs came up with the solution with the Higgs field. I know the whole thing is pretty abstract, but particle physics is abstract.

By the way: I think the basic idea comes from solid state physics.

Triplet room:How can you detect a HIGGS particle in the detector, how does it work exactly?

Dr. Matthias Schott: The Higgs particle itself decays into other particles in the particle detector so quickly that only its decay products can be detected. Which decay products these are depends entirely on the mass of the Higgs particle, which we do not yet know. If we assume, for example, that the Higgs particle is more than twice as heavy as two Z bosons, it usually breaks up into two Z bosons.

Test of dipole magnets
 
So now we just have to look for these two Z bosons. Unfortunately, these also disintegrate very quickly into other particles, for example into two electrons each. Electrons are stable particles and do not decay any further. So we are looking in the detector for four electrons that were formed approximately at the same time. The problem with this is that four electrons are very often formed when protons collide without a Higgs particle being involved. So you have to think for a long time about how to distinguish electrons that were created by chance from those that could have come from a Higgs boson. This is usually the main task of an experimental particle physicist.

Triplet room:According to the physicist Peter Higgs, the mass of the particles comes about through the HIGGS mechanism. According to Einstein's E = mc², mass "arises" when the energy content of a particle is increased. How do these two theories fit together?

Dr. Matthias Schott: The special theory of relativity is integrated in the standard model, it is even a fundamental component. So, in a way, they're not two theories. But now to the mass: Let us perhaps consider the mass of a proton. According to the standard model, a proton consists of three quarks. One would naively assume that the mass of the quarks is about 1/3 of the mass of the proton. However, this is wrong because the mass of the quarks is much, much smaller.

How then does the relatively large mass of the proton come about? Well, the quarks attract each other very strongly and are in a bound state. So a proton has a lot of "binding energy". And this binding energy behaves like a mass according to Einstein's E = mc². A large part of the total mass that we can observe in everyday life is actually only "binding energy". The mass of the quarks from the proton remains to be clarified. This is now generated by the Higgs mechanism.

Triplet room:Can one explain in simple terms how the HIGGS mechanism gives the particles their mass?

 
Black hole in ATLAS

Dr. Matthias Schott: In simple terms you can imagine the whole thing as follows: The Higgs particles couple or interact with all elementary particles that have mass. This interaction can be thought of as a kind of friction. For example, it is more difficult to accelerate an object in water than in a vacuum. This friction in the water can be interpreted as a kind of mass, since heavier objects are also more difficult to accelerate. The whole thing is only a picture, but in principle one can imagine that the particles get mass through the interaction with the Higgs field.

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